OKLAHOMA CITY (AP) Oklahoma City Thunder forward Nick Collison is retiring after 15 years in the NBA.

The 37-year-old Collison announced his decision Thursday through the team. The Thunder said Collison is among five NBA players to have spent the past 15 or more seasons all with one franchise.

"My goal was always to make a career out of basketball and I was blessed to be in the NBA for 15 seasons," Collison said in a statement.

The 6-foot-10 Collison did not give a reason for his retirement. He played in just 15 games this past season. His best season came in 2007-08, when he averaged 9.8 points and 9.4 rebounds in the last year before the Seattle SuperSonics relocated to Oklahoma City.

Collison was selected No. 12 overall out of Kansas by the Seattle Supersonics in 2003.

Thunder executive vice president and general manager Sam Presti said Collison was a player who set the course for the team at home in Oklahoma City. "Nick has helped define the standards we work by on a day-to-day basis, on and off the court," Presti said. "He has become synonymous with the Thunder shield."

Thunder chairman Clayton I. Bennett said that after purchasing the SuperSonics, the first thing he saw in the gym was Collison practicing his jump shot. That moment stuck with Bennett, who thanked Collison for being the same person today as he was then. "The Thunder will forever be a better organization because he was here," Bennett said.

Collison started 177 of his 910 career regular-season games, averaging 5.9 points and 5.2 rebounds. He and Russell Westbrook are the only two players to spend the first 10 years of the relocated franchise in Oklahoma City.

Collison thanked family, friends, teammates, coaches and fans for his career. "It would not have been possible to do it on my own," he said.